This invention relates to implantable medical devices (IMDs) for sensing physiological signals, monitoring and recording physiological events, and delivering therapy. In particular, the invention relates to telemetry-synchronized operation of multiple IMDs.
Pacemakers, cardioverter defibrillators, nerve stimulators, and drug delivery devices are examples of IMDs used to provide therapy over extended periods of time to a patient. These devices typically include sensors that are located on or in the IMD housing or are connected to the IMD by electrical leads. The IMD includes signal processing circuitry for processing physiologic signals from the sensors, and therapy delivery circuitry for controlling the delivery of therapy based upon the sensed physiologic signals. The therapy may include electrical stimulation of nerves, muscles, organs, or may be the delivery of therapeutic substances such as insulin or drugs.
The monitoring and recording of physiologic events in a patient's body over extended periods of time has important diagnostic, therapeutic, and research benefits. Ambulatory recorders have been developed for electrocardiogram (ECG), electroencephalogram (EEG), blood pressure, and other physiologic signals. Both externally worn monitors and implantable monitors have been developed. For example, the Klein et al. U.S. Pat. No. 5,987,352 describes an implantable long term ECG monitor that automatically detects arrhythmia and records ECG signals in memory. The recorded ECG signals can later be transferred by telemetry to an external device.
The human body is a complex organism with many interrelated systems. A physiologic condition may manifest itself concurrently or sequentially at different places in the body. Improved diagnosis and treatment may be aided by capturing data and delivering therapy based upon sensed physiologic signals from different portions of the body.